water banner

The USEPA’s Stormwater Program and NYSDEC’s state permit for MS4s

The USEPA’s Stormwater Program and NYSDEC’s state permit for MS4s *

The Environmental Protection Agency implemented the Stormwater Program in an effort to clean and improve the Nation’s surface and ground waters from polluted stormwater. Sections 305(b) and 303(d) of the Clean Water Act, in combination with the NYSDEC programs outlined above, shape the direction of stormwater efforts and regulations in New York. Remember that EPA is the federal agency that establishes the program and sets the guidelines, but gives the states the power to tighten and enforce those guidelines. Also recall that a TMDL is the total amount of pollutant the waterbody can receive daily and still meet Water Quality Standards, and many TMDLs sources are from polluted stormwater. An MS4 is a Municipal Separate Storm Sewer System or, the entire storm sewer system within a municipal boundary. The MS4 system does not include the sanitary system. There are no combined sewer systems in Rockland County (see CSO locations here). 

EPA’s Stormwater Program is divided into two phases. Phase I focuses on areas with populations of 100,000 or greater (such as New York City). Phase II focuses on areas with populations smaller than 100,000. Municipalities that fall under the Phase II Stormwater Program must obtain a permit from their state to address and discharge stormwater from their municipal storm sewer system (MS4) to receiving waterways. There are therefore a total of 23 municipalities in Rockland County that are required to abide by New York State Department of Environmental Conservation’s SPDES General Permit for Stormwater Discharges from Municipal Separate Storm Sewer Systems (i.e. ‘the NYSDEC MS4 Permit’). Part of these requirements are to provide opportunity for public involvement, and to implement a public education and outreach program to describe the impacts of stormwater discharges on waterbodies, illicit discharges, the Pollutant’s of Concern (POCs) and their sources, and the steps that contributors of these pollutants can take to reduce pollutants in stormwater runoff. Other parts include mapping of the storm sewer collection system, illicit discharge detection and elimination, and properly maintaining municipal facilities with potential to release POCs into local waters. 

If you are constructing a site that will require 1 or more acres of soil disturbance, you will be required to apply for the SPDES General Permit for Stormwater Discharges from Construction Activity . The New York State Stormwater Management Design Manual, linked to the permit page, is an important companion of the permit that outlines requirement for Green Infrastructure, and the stormwater management practices and methods that are acceptable in New York State. The permit plays a significant role in preventing soil erosion, sedimentation to waterways, and protecting water quality both during and after construction.

* The Stormwater Program falls under EPA’s National Pollutant Discharge Elimination System (NPDES) program, and is enforced through NYSDEC’s State Pollutant Discharge Elimination System (SPDES). 

Click here for additional cited works & resources.


Jennifer Zunino-Smith
Environmental Resource Educator
(845) 429-7085 x125

Last updated January 29, 2024